From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: Fri, 19 Dec 2014 20:57:49 +0000 (-0800)
Subject: Input: elan_i2c - check if device is there before really probing
X-Git-Tag: v4.1.52~277
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b881cc286c391e4d83432d186d10604e2227ff07;p=thirdparty%2Fkernel%2Fstable.git

Input: elan_i2c - check if device is there before really probing

[ Upstream commit c5928551fd41b2eecdad78fa2be2a4a13ed5fde9 ]

Before trying to properly initialize the touchpad and generate bunch of
errors, let's first see it there is anything at the given address. If we
get error, fail silently with -ENXIO.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---

diff --git a/drivers/input/mouse/elan_i2c_core.c b/drivers/input/mouse/elan_i2c_core.c
index fd5068b2542db..152d057ed87c3 100644
--- a/drivers/input/mouse/elan_i2c_core.c
+++ b/drivers/input/mouse/elan_i2c_core.c
@@ -972,6 +972,13 @@ static int elan_probe(struct i2c_client *client,
 		return error;
 	}
 
+	/* Make sure there is something at this address */
+	error = i2c_smbus_read_byte(client);
+	if (error < 0) {
+		dev_dbg(&client->dev, "nothing at this address: %d\n", error);
+		return -ENXIO;
+	}
+
 	/* Initialize the touchpad. */
 	error = elan_initialize(data);
 	if (error)